It is well known in the art to test printed circuit assemblies (PCA) in test fixtures which are vacuum powered. The positions on the PCA to be tested are lined up with a set of test probes in a test fixture. The pins are specifically positioned to test a given PCA design. It is often desirable to test two sets of positions on the PCA, a first set and a second set. In order to allow this it is known in the art to have dual height probes which are spring loaded and can be depressed downward. This allows the user to have a first set of pins, dual stage pins, which co tact the PCA in the first position and a second set, with a height smaller than the first set. The PCA can be tested on the first set and then depressed downward, compressing the first set of pins, until the second set of pins is also contacted. Or this can be done in reverse, with all the pins contacting first and the PCA being moved upward so that only the first set of pins are in contact. There is presently no self-actuating automatic, mechanical way to accomplish this for vacuum fixtures. What is needed is a self-actuating automatic release mechanism which provides for dual stage release of the test assembly, allowing for two stage testing.